Every project ends with a pile of marked-up drawings, a folder of photos and a request from someone in the site office: "Can we get the as-builts done?" How painful that is depends almost entirely on what happened during construction, and on what gets handed to the engineer.
Design drawings, IFC drawings and as-builts
It helps to be precise about the terms, because they get mixed up.
- Design drawings show intent. They evolve through revisions as the design matures.
- Issued for Construction (IFC) drawings are the frozen set the contractor builds from. They carry the engineer's signature for the design.
- As-built drawings (sometimes called as-constructed or record drawings) show what was actually built, including every deviation from IFC: the support that moved because of an unexpected cable tray, the member that was upsized because the specified section was not in stock, the extra stiffener the welder added.
The as-built is the document that future engineers, maintainers and auditors will treat as the truth. If it is wrong, every decision made from it inherits the error.
Why the signature is not a formality
Clients sometimes expect an as-built to be a drafting exercise: transcribe the redlines, update the title block, done. The reason an RPEQ has to sign it is that the redlines almost always contain engineering decisions that nobody formally reviewed at the time.
A pipe support moved 400 mm changes the span and the load on the adjacent supports. A substituted section might be stronger in bending but weaker in a different mode. A field-drilled hole in a flange plate changes the net section. Each of those has to be checked against the governing standard before an engineer can put their name to the drawing. Depending on the job that might mean AS 4100 for structural steel, AS 3990 for mechanical equipment steelwork, AS 1657 for platforms, walkways and ladders, AS 4041 for pressure piping or AS 1210 for pressure vessels.
That checking is a professional engineering service under Queensland's Professional Engineers Act, which is why an as-built signed only by the fabricator or a drafter is not accepted by certifiers or mine sites. When we say every drawing is checked against the standard before it carries a signature, this is what we mean.
Where as-builts are demanded
- Building certification. The certifier needs record drawings, usually alongside Form 15 design certificates and Form 16 inspection certificates, before final approval.
- Mine site management of change. A change is not closed out until the as-builts are in the site drawing system. Commissioning approvals are often held up on exactly this point.
- Handover and asset registers. Maintenance planning, spares and future modifications all start from the record drawings.
- Investigations. After an incident, the as-built is the first document the investigator asks for.
What to send for a fast turnaround
Turnaround time is set by completeness, not by drafting speed. A complete pack can be turned into signed as-builts in days. An incomplete one generates a round of questions, a site visit, or both. Send:
- The IFC drawings at their final revision, in native CAD if you have it (DWG or DXF, or the Inventor or SolidWorks model). PDFs work, but the drawings have to be redrawn and the risk of transcription errors goes up.
- Every redline. Marked-up prints from the fabricator, the installer and the supervisor, even where they seem to overlap. Contradictions between them are useful information.
- Photographs with scale. A tape measure or a known object in the frame turns a photo into evidence. Photograph connections, supports and anything that changed.
- Survey or scan data if the job had it. For congested piping, a laser scan is often cheaper than a second site visit.
- Material and inspection records. Mill certificates, weld maps, NDT reports and inspection test plans. If a section was substituted, the certificate tells us what actually went in.
- The site's drawing requirements. Title block, numbering, revision conventions and file formats for the site's document control system.
What slows things down
Three things account for most delays.
Changes made without review. If a change on site was never checked, the as-built process becomes a retrospective assessment. Sometimes it passes easily. Sometimes it does not, and the honest answer is that the drawing cannot be signed until the item is fixed. Involving the engineer when the change happens, even by a phone call and a photo, avoids this.
Missing dimensions. A photo of a moved support tells us it moved. It does not tell us where to. Write the measurement on the redline.
No native files. Redrawing a full set from PDF is the single largest time cost. If the original designer will release the CAD files, ask for them at the start of the job.
2D, 3D or both
Most sites still run on 2D record drawings, and that is what certifiers expect. For plant with a lot of piping or where future modifications are likely, a 3D as-built model pays for itself the first time someone wants to add a tie-in without a site visit. We produce both, and the 2D sheets are generated from the model so they stay consistent.
keep the redlines, photograph with a tape in shot, and call the engineer when something changes on site rather than at handover. Do that and your as-builts will come back signed quickly.